glsl - Structure of output of fragment shader?

Question

When writing a fragment shader in GLSL for Vulkan I guess I've learned by example that the color of the fragment can be output like this:

layout(location = 0) out vec4 outColor;

void main() {
    outColor = /*...*/;
}

My question is where in the Vulkan or GLSL spec is this specified? ie That the out variable of location 0 should contain the output color and its type can be (must be?) vec4?

In the Vulkan spec it doesn't seem to be mentioned in 9.9 Fragment Shaders, and 26 Fragment Operations just links back to 9.9.

The GLSL spec has a two paragraph overview 2.5 Fragment Processor, doesn't go into specifics. In 7.1.5. Fragment Shader Special Variables it lists global variables, but no mention of the "out" variable. There is some discussion under Layout Qualifiers, but doesn't seem very specific.

Any idea?

Answer 1

等待大神解答